The present invention relates to an igniter, and particularly relates to an ignition material for an igniter for actuating an inflatable vehicle occupant protection apparatus.
An inflatable vehicle occupant protection device, such as an air bag, is inflated by inflation gas provided by an inflator. The inflator typically contains ignitable gas generating material. The inflator further includes an igniter to ignite the gas generating material.
The igniter contains a charge of ignition material. The igniter also contains a bridgewire that is supported in a heat transferring relationship with the ignition material. When the igniter is actuated, an actuating level of electric current is directed through the bridgewire in the igniter. This causes the bridgewire to become resistively heated sufficiently to ignite the ignition material. The ignition material then produces ignition products that, in turn, ignite the gas generating material.
An example of an ignition material typically used for igniting a gas generating material is black powder. Black powder is composed of sulfur, charcoal, and potassium nitrate or sodium nitrate. Black powder has several drawbacks when used as an ignition material for igniting a gas generating material. There are restrictions on shipping black powder, and special precautions must be taken when manufacturing black powder. Moreover, black powder is not a completely satisfactory ignition material for LOVA gas generating materials or propellants because it is not sufficiently energetic to ignite the LOVA gas generating materials or propellants. Black powder also does not exhibit low vulnerability characteristics, such as resistance to thermal decomposition and ignition upon shock. Accordingly, it would be desirable to provide an ignition material that is a substitute for black powder and that would be more energetic than black powder as an ignition material, while at the same time exhibiting less vulnerability to thermal decomposition and ignition upon shock.
The present invention is an electrically actuatable igniter. The electrically actuatable igniter comprises a pair of electrodes. A heating element is electrically connected between said electrodes. An ignition material is in contact with the heating element. The ignition material includes an energetic composition. The energetic composition comprises, by weight of the energetic composition, about 60% to about 90% basic copper nitrate, up to about 20% supplemental oxidizer, about 5% to about 20% charcoal, and up to about 10% supplemental fuel.
The present invention is also directed to an energetic composition that comprises, by weight of the energetic composition about 65% to about 85% basic copper nitrate, up to about 10% supplemental oxidizer, about 10% to about 15% charcoal, and up to about 10% supplemental fuel.